基于AS3676设计的LED照明管理技术

本文介绍了AS3676主要特性, 应用方框图, 模拟LDO方框图, 升压DC/DC转换器方框图, 环境光传感器内部电路图以及LED功能测试电路图, 自动控制LED内部电路图和外接元件列表.

Aaustriamicrosystems公司的 AS3676 是高度集成的CMOS功率和照明管理单元,适嗯移动手机或其它以一节锂离子电池或3节NiMH 电池供电的设备.它集成了一个用于白背景光LED的升压DC/DC转换器,一个大功率电荷泵,一个ADC,13个电流沉,LED功能测试,一个两线串行接口和控制逻辑.
 
AS3676主要特性:

High-Efficiency Step Up DC/DC Converter

- Up to 26V/50mA for White LEDs

- Programmable Output Voltage with External Resistors and Serial Interface

- Over voltage Protection

High-Efficiency High-Power Charge Pump

- 1:1, 1:1.5, and 1:2 Mode

- Automatic Up Switching (can be disabled and 1:2 mode can be blocked)

- Output Current up to 400mA/500mA pulsed

- Efficiency up to 95%

- Very Low effective Resistance (2.5Ω typ. in 1:1.5)

- Only 4 External Capacitors Required:

2 x 1μF Flying Capacitors, 2 x 2.2μF Input/Output Capacitors

- Supports LCD White Backlight LEDs, or RGB LEDs

13 Current Sinks

- All 13 current sinks fully Programmable (8-bit) from: 0.15mA to 38.5mA (up to 75.6mA for
CURR30...CURR33)

- Three current sinks are High Voltage capable (CURR1, CURR2, CURR6)

- Programmable Hardware Control (Strobe, and Preview or PWM)

- Selectively Enable/Disable Current Sinks

- Dynamic Luminance Scaling (DLS) support to improve backlight operating time (can adjust any current source)

- Light Sensor input with internal hardware processing to control backlight according to ambient light using 3 groups - any current source can select one of the groups or no light sensor control

Internal PWM Generation

- 8 Bit resolution

- Autonomous Logarithmic up/down dimming

Led Pattern Generator

- Autonomous driving for Fun RGB LEDs

- Support indicator LEDs

10-bit Successive Approximation ADC

- 27μs Conversion Time

- Selectable Inputs: VANA/GPI, GPIO1/DLS, GPIO2/LIGHT, all current sources, VBAT, CPOUT, DCDC_FB

- Internal Temp. Measurement

- Light Sensor input with Java support (JSR-256): read ADC processed value

Support for automatic LED testing (open and shorted LEDs can be identified)

Strobe Timeout protection

- Up to 1600ms

- Three different timing modes

Two General Purpose Inputs/Output

- GPIO1/DLS, GPIO2/LIGHT

- Digital Input, Digital Output using VANA/GPI supply and Tristate

- GPIOs Programmable Pull-Up/Down

Programmable LDO

- 1.8 to 3.35V, 150mA

- Programmable via Serial Interface

Standby LDO always on

- Regulated 2.5V max. output 10mA

- 3μA Quiescent Current

Audio can be used to drive RGB LED(s)

- Color and Brightness depends on audio amplitude

Wide Battery Supply Range: 3.0 to 5.5V

Two Wire Serial Interface Control

Over current and Thermal Protection

WL-CSP30 3x2.5mm, 0.5mm pitch Package

AS3676应用:

Power- and lighting-management for mobile telephones and other 1-cell Li+ or 3-cell NiMH powered devices.


图1.AS3676方框图

图2.AS3676模拟LDO方框图

图3.AS3676升压DC/DC转换器方框图:电流反馈和过压保护

图4.AS3676升压DC/DC转换器详细方框图

图5.AS3676环境光传感器内部电路图

图6.AS3676 GPIO和VANA/GPI方框图

图7.AS3676 LED功能测试电路图

图8.AS3676自动控制LED内部电路图
外接元件列表: